//外部配置
include lua.conf;
//新系統(tǒng)地址
upstream new{
      server 192.168.1.103:8081;
}
//老系統(tǒng)地址
upstream old{
      server 192.168.1.103:8080;
}

//引入redis模塊，只能聯(lián)單機(jī)
local redis = require "resty.redis"
local cache = redis.new()
cache:set_timeout(60000)
//鏈接
local ok, err = cache.connect(cache, '192.168.19.10', 6379)
// 這里如果鏈接redis失敗，則轉(zhuǎn)發(fā)到@old對(duì)應(yīng)的服務(wù)器 (傳統(tǒng)服務(wù))
if not ok then
    ngx.exec("@old")
    return
end

//如果nginx只有一層分發(fā)層，這下面四行代碼可以不寫(xiě)
local local_ip = ngx.req.get_headers()["X-Real-IP"]
if local_ip == nil then
    local_ip  = ngx.req.get_headers()["x_forwarded_for"]
end

//從remote_addr變量中拿到客戶端ip，同樣nginx只有一層的時(shí)候此變量為客戶端ip，多層不是
if local_ip == nil then
    local_ip = ngx.var.remote_addr
end

//在redis中根據(jù)客戶端ip獲取是否存在值; redis中存放的是key:ip val:ip, 存放的ip訪問(wèn)微服務(wù)
local intercept = cache:get(local_ip)
//如果存在則轉(zhuǎn)發(fā)到@new對(duì)應(yīng)的服務(wù)器(微服務(wù))
if intercept == local_ip then
    ngx.exec("@new")
    return
end
//如果不存在，則轉(zhuǎn)發(fā)到@old對(duì)應(yīng)的服務(wù)器(傳統(tǒng)服務(wù))
ngx.exec("@old")
//關(guān)閉客戶端
local ok, err = cache.close()
if not ok then
    ngx.say("failed to close:", err)
    return
end

//這里緩存服務(wù)地址
backend = "http://192.168.1.156:8080"
//緩存服務(wù)訪問(wèn)路徑
local method = "httptest"
local requestBody = "/"..method
//模塊
local http = require("resty.http")
local httpc = http.new()
//設(shè)置超時(shí)時(shí)間
httpc:set_timeout(1000)
//發(fā)送請(qǐng)求
local resp, err = httpc:request_uri(backend, {--
    method = "GET", --
    path = requestBody,
    keepalive = false
})
//如果請(qǐng)求失敗訪問(wèn)老系統(tǒng)
if not resp then--
    ngx.exec("@old")----
    return--
end
//緩存服務(wù)取回ip
local isHave = resp.body
//關(guān)閉連接
httpc:close()
//請(qǐng)求ip
local local_ip = ngx.var.remote_addr
//命中則訪問(wèn)微服務(wù)
if isHave == local_ip then
    ngx.exec("@new")
    return
end
//沒(méi)命中訪問(wèn)老系統(tǒng)
ngx.exec("@old")

backend = "http://192.168.1.156:8080"
//加載共享內(nèi)存
local cache_ngx = ngx.shared.rediscache
local local_ip = ngx.var.remote_addr
//優(yōu)先從本地緩存中去取
local cacheip = cache_ngx:get(local_ip)
//本地緩存中不存在，去緩存服務(wù)中去取，然后加載到本地緩存
if cacheip == "" or cacheip == nil then
    local http = require("resty.http")
    local httpc = http.new()
    httpc:set_timeout(1000)
    local method = "httptest"
    local requestBody = "/" .. method
    local resp, err = httpc:request_uri(backend, {
        method = "GET",
        path = requestBody,
        keepalive=false
    })
    if not resp then
        ngx.exec("@new")
        return
    end
    cacheip = resp.body
    httpc:close()
    //加載到本地緩存，設(shè)置過(guò)期時(shí)間
    cache_ngx:set(local_ip, cacheip, 10*60)
end
if cacheip == local_ip then
    ngx.exec("@new")
    return
end
ngx.exec("@old")